Gene and protein expression profiles associated with the therapeutic efficacy of irinotecan

ABSTRACT

The present invention includes gene and protein expression profiles indicative of whether a cancer patient is likely to respond to treatment with irinotecan. By identifying such responsiveness, a treatment provider may determine in advance those patients who would benefit from such treatment, as well as identify alternative therapies for non-responders. The present invention further provide methods of using the gene and/or protein expression profiles and assays for identifying the presence of a gene and/or protein expression profile in a patient sample.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.provisional Application Ser. No. 60/846,298 filed Sep. 21, 2006 andApplication Ser. No. 60/906,438 filed Mar. 12, 2007, the entirety ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Patients diagnosed with cancer are faced with costly and often painfultreatment options. These treatments may be ineffective in asubpopulation of patients, and as a result, these patients endure thesetreatments without little or no therapeutic benefit. Some patients mayreact adversely to certain agents causing additional suffering andpossibly death.

Ineffective treatment also is problematic because time is a key variablewhen treating cancer. A treatment provider has a far greater chance ofcontaining and managing the disease if the cancer is diagnosed at anearly stage and treated with a therapeutically effective agent. An agentmay provide great therapeutic benefits if administered at an early stageof the disease; however, with the passage of time, the same agent maycease to be effective.

Colorectal cancer is an example of a condition where early diagnosis iskey for effective treatment. Colorectal cancer is cancer that developsin the colon or the rectum. The walls of the colon and rectum haveseveral layers of tissue. Colorectal cancer often starts in theinnermost layer and can grow through some or all of the other layers;the stage (extent of spread) of a colorectal cancer depends to a greatdegree on how deeply it has grown into these layers.

Chemotherapy is often used for treating colorectal cancer. Irinotecanhydrochloride (CAMPTOSAR®) is a chemotherapeutic agent indicated forfirst-line therapy of colorectal cancers. As with many chemotherapeuticagents, administration of irinotecan hydrochloride (“irinotecan”) oftencauses deleterious side effects for the patient, and some patients donot respond well to the treatment. Some patients thus undergo treatmentwith irinotecan and suffer the painful side effects only to laterrealize that the agent has not been therapeutically beneficial to theircondition. In addition to the unnecessary suffering, critical time islost in determining an alternative treatment.

SUMMARY OF THE INVENTION

The present invention provides gene and protein expression profiles andmethods of using them to identify those patients who are likely torespond to treatment with irinotecan (these patients are referred to as“responders”), as well as those patients who are not likely to benefitfrom such treatment (these patients are referred to as“non-responders”). The present invention allows a treatment provider toidentify those patients who are responders to irinotecan treatment, andthose who are not non-responders to such treatment, prior toadministration of the agent.

In one aspect, the present invention comprises gene expression profiles,also referred to as “gene signatures,” that are indicative of a cancerpatient's tendency to respond to treatment with irinotecan. The geneexpression profile (GEP) comprises at least one, and preferably aplurality, of genes selected from the group consisting of ERBB2, GRB7,Erk1 kinase, JNK1 kinase, BCL2, phospho-GSK-3beta, MMP11, CTSL2, CCNB1,BIRC5, MK167, STK6, MRP14, phospho-Akt, CD68, BAG1 and GSTM1. The genesignature may further include reference or control genes. The currentlypreferred reference genes are ACTB, GAPD, GUSB, RPLP0 and TFRC.According to the invention, some or all of theses genes aredifferentially expressed (e.g., up-regulated or down-regulated) inpatients who are responders to irinotecan therapy. Specifically, ERBB2,GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD68 and BAG1 areup-regulated (over-expressed) and Erk1 kinase, phospho-GSK-3beta, MMP11,CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1 are down-regulated(under-expressed) in patients who are responders to irinotecan.Reference genes ACTB, GAPD, GUSB, RPLP0 and TFRC are up-regulated(over-expressed).

The present invention further comprises protein expression profiles thatare indicative of a cancer patient's tendency to respond to treatmentwith irinotecan. The protein expression profiles comprise those proteinsencoded by the genes of the GEP that also are differentially expressedin colon cancers that are responsive to irinotecan therapy. The presentprotein expression profile (PEP) comprises at least one, and preferablya plurality, of proteins encoded by the genes selected from the groupconsisting of ERBB2, GRB7, Erk1 kinase, JNK1 kinase, BCL2,phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, MK167, STK6, MRP14,phospho-Akt, CD68, BAG1 and GSTM1. The protein expression profile mayfurther include proteins encoded by reference genes. The currentlypreferred reference genes are ACTB, GAPD, GUSB, RPLP0 and TFRC.According to the invention, some or all of theses proteins aredifferentially expressed (e.g., up-regulated or down-regulated) inpatients who are responders to irinotecan therapy. Specifically,proteins encoded by the following genes are up-regulated(over-expressed): ERBB2, GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt,CD68 and BAG1; and proteins encoded by the following genes aredown-regulated (under expressed): Erk1 kinase, phospho-GSK-3beta, MMP11,CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1, in patients who areresponders to irinotecan. Reference proteins ACTB, GAPD, GUSB, RPLP0 andTFRC are up-regulated (over-expressed).

The gene and protein expression profiles of the present invention(referred to hereinafter as GPEPs) comprise a group of genes andproteins that are differentially expressed (e.g., up-regulated ordown-regulated) in patients who are responders to irinotecan therapyrelative to expression of the same genes in patients who arenon-responders to this therapy. Patients having tumors that arenon-responsive to irinotecan often experience recurrence of theirdisease or disease-related death. The GPEPs of the present inventionthus can be used to predict not only responsiveness of a colon cancer toirinotecan therapy, but also the likelihood of recurrence of the cancerand/or disease-related death.

The present invention further comprises a method of determining if apatient is a responder or non-responder to treatment with irinotecan.The method comprises obtaining a tumor sample from the patient,determining the gene and/or protein expression profile of the sample,and determining from the gene or protein expression profile whether atleast one, preferably at least 4, more preferably at least 10, and mostpreferably at least 16 of the genes selected from the group consistingof ERBB2, GRB7, Erk 1 kinase, JNK1 kinase, BCL2, phospho-GSK-3beta,MMP11, CTSL2, CCNB1, BIRC5, MK167, STK6, MRP14, phospho-Akt, CD68, BAG1and GSTM1, or at least one protein selected from the proteins encoded bythese genes, is differentially expressed in the sample. From thisinformation, the treatment provider can ascertain whether the patient islikely to benefit from irinotecan therapy. The present method also canbe used to predict late recurrence and disease related death associatedwith the therapy.

The present invention further comprises assays for determining the geneand/or protein expression profile in a patient's sample, andinstructions for using the assay. The assay may be based on detection ofnucleic acids (e.g., using nucleic acid probes specific for the nucleicacids of interest) or proteins or peptides (e.g., using antibodiesspecific for the proteins/peptides of interest). In a currentlypreferred embodiment, the assay comprises an immunohistochemistry (IHC)test in which tissue samples, preferably arrayed in a tissue microarray(TMA), and are contacted with antibodies specific for theproteins/peptides identified in the GPEP as being indicative of apatient's responsiveness to irinotecan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the survival rates for patients treated withirinotecan HCl correlated with the present gene expression profilepredicting responsiveness to irinotecan therapy.

DETAILED DESCRIPTION

The present invention provides gene and protein expression profiles andtheir use for predicting a patient's responsiveness to a cancertreatment. More specifically, the present GPEPs are indicative ofwhether a patient is a responder or a non-responder to treatment withirinotecan. Those patients identified as responders using the presentGPEP are likely to benefit from irinotecan therapy, whereas thosepatients identified as non-responders may avoid unnecessary treatmentwith irinotecan and consider other treatment options in a timely manner.The present GPEPs also can be used to predict the likelihood ofrecurrence of colon cancer and disease related death associated withirinotecan therapy in some patients.

Irinotecan is a chemotherapeutic agent which belongs to the group ofmedicines called antineoplastics. It is indicated as first-line therapyfor treating cancers of the colon or rectum. Irinotecan interferes withthe growth of cancer cells, which are eventually destroyed. Because thegrowth of normal cells may also be affected by the medicine, othereffects also may occur. These other effects may include: increasedsweating and production of saliva, diarrhea, nausea (feeling sick) andvomiting, loss of appetite, lowered resistance to infection, bruising orbleeding, anemia, hair loss, tiredness and a general feeling ofweakness. The present invention enables the treatment provider todetermine in advance those patients likely to benefit from irinotecantreatment, and to consider alternative treatment options fornon-responders. It is understood that treatment with irinotecan includesadministering irinotecan alone and in combination with other therapeuticagents or adjuvants. The current indications for CAMPTOSAR® includeadministering irinotecan HCl in combination with 5-fluorouracil (5-FU)and leucovorin (LV) as first-line therapy for metastatic colorectalcancer, and alone as a second-line therapy for patients whose diseasehas returned or progressed following initial 5-FU therapy.

The genes comprising the present GEP include: ERBB2, GRB7, Erk1 kinase,JNK1 kinase, BCL2, phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, MK167,STK6, MRP14, phospho-Akt, CD68, BAG1 and GSTM1. In a preferredembodiment, the present gene expression profile further includes thefollowing reference genes: ACTB, GAPD, GUSB, RPLP0 and TFRC. The NCBIAccession Number of a variant of each of these genes is set forth inTable 1; other variants exist which can be readily ascertained byreference to an appropriate database such as NCBI Entrez(www.ncbi.nlm.nih.gov/gquery), and these variants are encompassed by thepresent invention. These genes are either up- or down-regulated inpatients that are responsive to irinotecan therapy, and not in inpatients that experience late recurrence of their disease or diseaserelated death associated with the therapy. Accordingly, it is possibleto determine in advance if a patient is likely to benefit fromirinotecan therapy by obtaining a gene expression profile from thepatient's tissue, and determining whether one or more of the genes inthe present GEP is up- or down-regulated. Table 1 identifies the genesand indicates whether these genes are up- or down-regulated in patientsthat are responders to irinotecan therapy. TABLE 1 UP- or DOWN- NCBIGENE NAME ALT GENE NAME REGULATION ACCESSION NO. SEQ ID NO. HER2Amplicon ERBB2 HER2 Up NM_004448 1 GRB7 Up NM_005310 2 ER ExpressionCluster Erk1 kinase Down X60188 3 JNK1 kinase Up NM_002750 4 BCL2 UpNM_000633 5 GSK-3-beta Down NM_002093 6 Invasion Group MMP11 STMY3;stromolysin 3 Down NM_005940 7 CTSL2 cathepsin L2 Down NM_001333 8Proliferation Cluster CCNB1 cyclin B1 Down NM_031966 9 BIRC5 SURV;survivin Down NM_001168 10 MKI67 Ki-67 antigen Up NM_002417 11 STK6STK15; BTAK Down NM_003600 12 Akt (Ser473) Up NM_005163 13 Other GenesCD68 Up NM_001251 14 BAG1 Up NM_004323 15 GSTM1glutathione-s-transferase Down NM_146421 16 M1 MRP14 S100 calciumbinding Down NM_002965 17 protein A9 Reference Genes ACTB β-Actin UpNM_001101 18 GAPD GAPDH Up NM_002046 19 GUSB GUS Up NM_000181 20 RPLP0Up NM_001002 21 TFRC Up NM_003234 22

In a preferred aspect of the present invention, the gene profile of thepresent invention comprises at least four, preferably between four andten, more preferably at least ten, and most preferably at least sixteen,of the genes in the present GEP, up- or down-regulated as applicable,together with one or more reference genes.

The gene expression profiles of the invention can be used to predict theresponsiveness of a colon cancer patient to irinotecan therapy. In oneaspect, the present method comprises (a) obtaining a gene expressionprofile from a biological sample of a patient afflicted with coloncancer; (b) determining from the gene expression profile whether one ormore of the following genes are up-regulated (over-expressed): ERBB2,GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD68 and BAG1; and/orwhether at least one of the following genes are down-regulated(under-expressed): Erk1 kinase, phospho-GSK-3beta, MMP11, CTSL2, CCNB1,BIRC5, STK6, MRP14 and GSTM1. Preferably, expression of at least tworeference genes also is measured. The predictive value of the geneprofile for determining response to irinotecan increases with the numberof these genes that are found to be up- or down-regulated in accordancewith the invention. Preferably, at least about four, more preferably atleast about ten and most preferably at least about sixteen of the genesin the present GPEP are differentially expressed.

The present invention further comprises protein expression profiles thatare indicative of a cancer patient's tendency to respond to treatmentwith irinotecan. The protein expression profile comprises at least one,preferably a plurality, of proteins encoded by the genes selected fromthe group consisting of ERBB2, GRB7, Erk1 kinase, JNK1 kinase, BCL2,phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, MK167, STK6, MRP14,phospho-Akt, CD68, BAG1 and GSTM1. According to the invention, some orall of theses proteins are differentially expressed (e.g., up-regulatedor down-regulated) in patients who are responders to irinotecan therapy.Specifically, the proteins encoded by the following genes areup-regulated (over-expressed): ERBB2, GRB7, JNK1 kinase, BCL2, MK167,phospho-Akt, CD68 and BAG1 and the proteins encoded by the followinggenes are down-regulated (under expressed): Erk1 kinase,phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1, inpatients who are responders to irinotecan. The following reference genesmay be included: ACTB, GAPD, GUSB, RPLP0 and TFRC.

Table 2 lists the genes in the present GPEP and a variant of a proteinencoded thereby. Table 2 also indicates whether expression of theprotein is up- or down-regulated in patients responsive to irinotecantherapy. Table 2 includes the NCBI Accession No. of a variant of eachprotein; other variants of these proteins exist, which can be readilyascertained by reference to an appropriate database such as NCBI Entrez(www.ncbi.nlm.nih.gov/gquery). Alternate names for the proteins listedin Table 2 also can be determined from the NCBI site. TABLE 2 UP- ORDOWN- REGULATION NCBI Accession SEQ ID NO. GENE NAME PROTEIN NAME(S) ofPROTEIN No. of Protein of Protein ERBB2 ErbB-2; HER-2 Up NP_004439 23GRB7 GRB7; growth factor Up NP_005301 24 receptor-bound protein 7 Erk1kinase Erk1 kinase; mitogen Down P 27361 25 activated protein kinase 3JNK1 kinase JNK1 Kinase Up NP_002741 26 BCL2 Bcl-2; B-cell lymphoma UpNP_000624 27 protein 2 GSK-3-beta Phospho-GSK-3 beta; Down NP_002084 28glycogen synthase kinase 3 beta MMP11 STMY3; stromolysin 3; DownNP_005931 29 matrix metalloproteinase 11 CTSL2 cathepsin L2 DownNP_001324 30 CCNB1 cyclin B1 Down NP_114172 31 BIRC5 BIRC5; survivinDown NP_001159 32 MKI67 Ki-67 antigen Up NP_002408 33 STK6 STK15; BTAK;aurora-A Down NP_003591 34 Akt Phospho-akt; v-akt Up NP_005154 35 murinethyoma viral oncogene; RAC protein kinase alpha CD68 CD68 antigen; UpNP_001242 36 macrosialin BAG1 Bcl-2 associated Up NP_004314 37athanogene GSTM1 glutathione-s-transferase Down NP_666533 38 M1 ACTBβ-Actin Up NP_001092 39 GAPD GAPD Up NP_002037 40 GUSB GUS; gluuronidasebeta Up NP_000172 41 RPLP0 Ribosomal protein P0 Up NP_000993 42 TFRCTransferrin receptor Up NP_003225 43 MRP14 S100 calcium binding DownNP_002956 44 protein A9

DEFINITIONS

For convenience, the meaning of certain terms and phrases employed inthe specification, examples, and appended claims are provided below. Thedefinitions are not meant to be limiting in nature and serve to providea clearer understanding of certain aspects of the present invention.

The term “genome” is intended to include the entire DNA complement of anorganism, including the nuclear DNA component, chromosomal orextrachromosomal DNA, as well as the cytoplasmic domain (e.g.,mitochondrial DNA).

The term “gene” refers to a nucleic acid sequence that comprises controland coding sequences necessary for producing a polypeptide or precursor.The polypeptide may be encoded by a full length coding sequence or byany portion of the coding sequence. The gene may be derived in whole orin part from any source known to the art, including a plant, a fungus,an animal, a bacterial genome or episome, eukaryotic, nuclear or plasmidDNA, cDNA, viral DNA, or chemically synthesized DNA. A gene may containone or more modifications in either the coding or the untranslatedregions that could affect the biological activity or the chemicalstructure of the expression product, the rate of expression, or themanner of expression control. Such modifications include, but are notlimited to, mutations, insertions, deletions, and substitutions of oneor more nucleotides. The gene may constitute an uninterrupted codingsequence or it may include one or more introns, bound by the appropriatesplice junctions. The Term “gene” as used herein includes variants ofthe genes identified in Table 1.

The term “gene expression” refers to the process by which a nucleic acidsequence undergoes successful transcription and translation such thatdetectable levels of the nucleotide sequence are expressed.

The terms “gene expression profile” or “gene signature” refer to a groupof genes expressed by a particular cell or tissue type wherein presenceof the genes taken together or the differential expression of suchgenes, is indicative/predictive of a certain condition.

The term “nucleic acid” as used herein, refers to a molecule comprisedof one or more nucleotides, i.e., ribonucleotides, deoxyribonucleotides,or both. The term includes monomers and polymers of ribonucleotides anddeoxyribonucleotides, with the ribonucleotides and/ordeoxyribonucleotides being bound together, in the case of the polymers,via 5′ to 3′ linkages. The ribonucleotide and deoxyribonucleotidepolymers may be single or double-stranded. However, linkages may includeany of the linkages known in the art including, for example, nucleicacids comprising 5′ to 3′ linkages. The nucleotides may be naturallyoccurring or may be synthetically produced analogs that are capable offorming base-pair relationships with naturally occurring base pairs.Examples of non-naturally occurring bases that are capable of formingbase-pairing relationships include, but are not limited to, aza anddeaza pyrimidine analogs, aza and deaza purine analogs, and otherheterocyclic base analogs, wherein one or more of the carbon andnitrogen atoms of the pyrimidine rings have been substituted byheteroatoms, e.g., oxygen, sulfur, selenium, phosphorus, and the like.Furthermore, the term “nucleic acid sequences” contemplates thecomplementary sequence and specifically includes any nucleic acidsequence that is substantially homologous to the both the nucleic acidsequence and its complement.

The terms “array” and “microarray” refer to the type of genes orproteins represented on an array by oligonucleotides or protein-captureagents, and where the type of genes or proteins represented on the arrayis dependent on the intended purpose of the array (e.g., to monitorexpression of human genes or proteins). The oligonucleotides orprotein-capture agents on a given array may correspond to the same type,category, or group of genes or proteins. Genes or proteins may beconsidered to be of the same type if they share some commoncharacteristics such as species of origin (e.g., human, mouse, rat);disease state (e.g., cancer); functions (e.g., protein kinases, tumorsuppressors); same biological process (e.g., apoptosis, signaltransduction, cell cycle regulation, proliferation, differentiation).For example, one array type may be a “cancer array” in which each of thearray oligonucleotides or protein-capture agents correspond to a gene orprotein associated with a cancer. An “epithelial array” may be an arrayof oligonucleotides or protein-capture agents corresponding to uniqueepithelial genes or proteins. Similarly, a “cell cycle array” may be anarray type in which the oligonucleotides or protein-capture agentscorrespond to unique genes or proteins associated with the cell cycle.

The term “cell type” refers to a cell from a given source (e.g., atissue, organ) or a cell in a given state of differentiation, or a cellassociated with a given pathology or genetic makeup.

The term “activation” as used herein refers to any alteration of asignaling pathway or biological response including, for example,increases above basal levels, restoration to basal levels from aninhibited state, and stimulation of the pathway above basal levels.

The term “differential expression” refers to both quantitative as wellas qualitative differences in the temporal and tissue expressionpatterns of a gene or a protein in diseased tissues or cells versusnormal adjacent tissue. For example, a differentially expressed gene mayhave its expression activated or completely inactivated in normal versusdisease conditions, or may be up-regulated (over-expressed) ordown-regulated (under-expressed) in a disease condition versus a normalcondition. Such a qualitatively regulated gene may exhibit an expressionpattern within a given tissue or cell type that is detectable in eithercontrol or disease conditions, but is not detectable in both. Statedanother way, a gene or protein is differentially expressed whenexpression of the gene or protein occurs at a higher or lower level inthe diseased tissues or cells of a patient relative to the level of itsexpression in the normal (disease-free) tissues or cells of the patientand/or control tissues or cells.

The term “detectable” refers to an RNA expression pattern which isdetectable via the standard techniques of polymerase chain reaction(PCR), reverse transcriptase-(RT) PCR, differential display, andNorthern analyses, which are well known to those of skill in the art.Similarly, protein expression patterns may be “detected” via standardtechniques such as Western blots.

The term “complementary” refers to the topological compatibility ormatching together of the interacting surfaces of a probe molecule andits target. The target and its probe can be described as complementary,and furthermore, the contact surface characteristics are complementaryto each other. Hybridization or base pairing between nucleotides ornucleic acids, such as, for example, between the two strands of adouble-stranded DNA molecule or between an oligonucleotide probe and atarget are complementary.

The term “biological sample” refers to a sample obtained from anorganism (e.g., a human patient) or from components (e.g., cells) of anorganism. The sample may be of any biological tissue or fluid. Thesample may be a “clinical sample” which is a sample derived from apatient. Such samples include, but are not limited to, sputum, blood,blood cells (e.g., white cells), amniotic fluid, plasma, semen, bonemarrow, and tissue or fine needle biopsy samples, urine, peritonealfluid, and pleural fluid, or cells therefrom. Biological samples mayalso include sections of tissues such as frozen sections taken forhistological purposes. A biological sample may also be referred to as a“patient sample.”

A “protein” means a polymer of amino acid residues linked together bypeptide bonds. The term, as used herein, refers to proteins,polypeptides, and peptides of any size, structure, or function.Typically, however, a protein will be at least six amino acids long. Ifthe protein is a short peptide, it will be at least about 10 amino acidresidues long. A protein may be naturally occurring, recombinant, orsynthetic, or any combination of these. A protein may also comprise afragment of a naturally occurring protein or peptide. A protein may be asingle molecule or may be a multi-molecular complex. The term proteinmay also apply to amino acid polymers in which one or more amino acidresidues is an artificial chemical analogue of a corresponding naturallyoccurring amino acid.

A “fragment of a protein,” as used herein, refers to a protein that is aportion of another protein. For example, fragments of proteins maycomprise polypeptides obtained by digesting full-length protein isolatedfrom cultured cells. In one embodiment, a protein fragment comprises atleast about six amino acids. In another embodiment, the fragmentcomprises at least about ten amino acids. In yet another embodiment, theprotein fragment comprises at least about sixteen amino acids.

As used herein, an “expression product” is a biomolecule, such as aprotein, which is produced when a gene in an organism is expressed. Anexpression product may comprise post-translational modifications.

The term “protein expression” refers to the process by which a nucleicacid sequence undergoes successful transcription and translation suchthat detectable levels of the amino acid sequence or protein areexpressed.

The terms “protein expression profile” or “protein expression signature”refer to a group of proteins expressed by a particular cell or tissuetype (e.g., neuron, coronary artery endothelium, or disease tissue),wherein presence of the proteins taken together or the differentialexpression of such proteins, is indicative/predictive of a certaincondition.

The term “antibody” means an immunoglobulin, whether natural orpartially or wholly synthetically produced. All derivatives thereof thatmaintain specific binding ability are also included in the term. Theterm also covers any protein having a binding domain that is homologousor largely homologous to an immunoglobulin binding domain. An antibodymay be monoclonal or polyclonal. The antibody may be a member of anyimmunoglobulin class, including any of the human classes: IgG, IgM, IgA,IgD, and IgE.

The term “antibody fragment” refers to any derivative of an antibodythat is less than full-length. In one aspect, the antibody fragmentretains at least a significant portion of the full-length antibody'sspecific binding ability, specifically, as a binding partner. Examplesof antibody fragments include, but are not limited to, Fab, Fab′,F(ab′)₂, scFv, Fv, dsFv diabody, and Fd fragments. The antibody fragmentmay be produced by any means. For example, the antibody fragment may beenzymatically or chemically produced by fragmentation of an intactantibody or it may be recombinantly produced from a gene encoding thepartial antibody sequence. Alternatively, the antibody fragment may bewholly or partially synthetically produced. The antibody fragment maycomprise a single chain antibody fragment. In another embodiment, thefragment may comprise multiple chains that are linked together, forexample, by disulfide linkages. The fragment may also comprise amultimolecular complex. A functional antibody fragment may typicallycomprise at least about 50 amino acids and more typically will compriseat least about 200 amino acids.

Determination of Gene Expression Profiles

The method used to identify and validate the present gene expressionprofiles indicative of whether a colon cancer patient will respond totreatment with irinotecan is described below. Other methods foridentifying gene and/or protein expression profiles are known; any ofthese alternative methods also could be used. See, e.g., Chen et al.,NEJM, 356(1):11-20 (2007); Lu et al., PLOS Med., 3(12):e467 (2006);Golub et al., Science, 286:531-537 (1999).

The present method utilizes parallel testing in which, in one track,those genes which are over-/under-expressed as compared to normal(non-cancerous) tissue samples are identified, and, in a second track,those genes comprising chromosomal insertions or deletions as comparedto normal samples are identified, from the same samples. These twotracks of analysis produce two sets of data. The data are analyzed usingan algorithm which identifies the genes of the gene expression profile(i.e., those genes that are differentially expressed in cancer tissue).Positive and negative controls may be employed to normalize the results,including eliminating those genes and proteins that also aredifferentially expressed in normal tissues from the same patients, andconfirming that the gene expression profile is unique to the cancer ofinterest.

In the present instance, as an initial step, biological samples wereacquired from patients afflicted with colorectal cancer. Approximatelyfive-hundred (500) tissue samples obtained from colorectal cancerpatients were used, including tumor tissue and adjacent normal(undiseased) colon tissue. The tissue samples were obtained frompatients suffering from various stages of colon cancer, and includedthose obtained from patients who have been treated with irinotecan. Allof the patients were responders to irinotecan therapy. Clinicalinformation associated with each sample, including treatment withirinotecan and the outcome of the treatment, was recorded in a database.Clinical information also includes information such as age, sex, medicalhistory, treatment history, symptoms, family history, recurrence(yes/no), etc. Control samples, including samples of normal(non-cancerous) tissue also were acquired from the same patients.Samples of normal undiseased colon tissue from a set of healthyindividuals were used as positive controls, and colon tumor samples frompatients who were non-responders to irinotecan therapy were used asnegative controls.

Gene expression profiles (GEPs) then were generated from the biologicalsamples based on total RNA according to well-established methods.Briefly, a typical method involves isolating total RNA from thebiological sample, amplifying the RNA, synthesizing cDNA, labeling thecDNA with a detectable label, hybridizing the cDNA with a genomic array,such as the Affymetrix U133 GeneChip, and determining binding of thelabeled cDNA with the genomic array by measuring the intensity of thesignal from the detectable label bound to the array. See, e.g., themethods described in Lu, et al., Chen, et al. and Golub, et al., supra,and the references cited therein, which are incorporated herein byreference. The resulting expression data are input into a database.

MRNAs in the tissue samples can be analyzed using commercially availableor customized probes or oligonucleotide arrays, such as cDNA oroligonucleotide arrays. The use of these arrays allows for themeasurement of steady-state mRNA levels of thousands of genessimultaneously, thereby presenting a powerful tool for identifyingeffects such as the onset, arrest or modulation of uncontrolled cellproliferation. Hybridization and/or binding of the probes on the arraysto the nucleic acids of interest from the cells can be determined bydetecting and/or measuring the location and intensity of the signalreceived from the labeled probe or used to detect a DNA/RNA sequencefrom the sample that hybridizes to a nucleic acid sequence at a knownlocation on the microarray. The intensity of the signal is proportionalto the quantity of cDNA or mRNA present in the sample tissue. Numerousarrays and techniques are available and useful. Methods for determininggene and/or protein expression in sample tissues are described, forexample, in U.S. Pat. No. 6,271,002; U.S. Pat. No. 6,218,122; U.S. Pat.No. 6,218,114; and U.S. Pat. No. 6,004,755; and in Wang et al., J. Clin.Oncol., 22(9):1564-1671 (2004); Golub et al, (supra); and Schena et al.,Science, 270:467-470 (1995); all of which are incorporated herein byreference.

The gene analysis aspect utilized in the present method investigatesgene expression as well as insertion/deletion data. As a first step, RNAwas isolated from the tissue samples and labeled. Parallel processeswere run on the sample to develop two sets of data: (1)over-/under-expression of genes based on mRNA levels; and (2)chromosomal insertion/deletion data. These two sets of data were thencorrelated by means of an algorithm. Over-/under-expression of the genesin each cancer tissue sample were compared to gene expression in thenormal (non-cancerous) samples, and a subset of genes that weredifferentially expressed in the cancer tissue was identified.Preferably, levels of up- and down-regulation are distinguished based onfold changes of the intensity measurements of hybridized microarrayprobes. A difference of about 2.0 fold or greater is preferred formaking such distinctions, or a p-value of less than about 0.05. That is,before a gene is said to be differentially expressed in diseased versusnormal cells, the diseased cell is found to yield at least about 2 timesgreater or less intensity of expression than the normal cells.Generally, the greater the fold difference (or the lower the p-value),the more preferred is the gene for use as a diagnostic or prognostictool. Genes selected for the gene signatures of the present inventionhave expression levels that result in the generation of a signal that isdistinguishable from those of the normal or non-modulated genes by anamount that exceeds background using clinical laboratoryinstrumentation.

Statistical values can be used to confidently distinguish modulated fromnon-modulated genes and noise. Statistical tests can identify the genesmost significantly differentially expressed between diverse groups ofsamples. The Student's t-test is an example of a robust statistical testthat can be used to find significant differences between two groups. Thelower the p-value, the more compelling the evidence that the gene isshowing a difference between the different groups. Nevertheless, sincemicroarrays allow measurement of more than one gene at a time, tens ofthousands of statistical tests may be asked at one time. Because ofthis, it is unlikely to observe small p-values just by chance, andadjustments using a Sidak correction or similar step as well as arandomization/permutation experiment can be made. A p-value less thanabout 0.05 by the t-test is evidence that the expression level of thegene is significantly different. More compelling evidence is a p-valueless then about 0.05 after the Sidak correction is factored in. For alarge number of samples in each group, a p-value less than about 0.05after the randomization/permutation test is the most compelling evidenceof a significant difference.

Another parameter that can be used to select genes that generate asignal that is greater than that of the non-modulated gene or noise isthe measurement of absolute signal difference. Preferably, the signalgenerated by the differentially expressed genes differs by at leastabout 20% from those of the normal or non-modulated gene (on an absolutebasis). It is even more preferred that such genes produce expressionpatterns that are at least about 30% different than those of normal ornon-modulated genes.

This differential expression analysis can be performed usingcommercially available arrays, for example, Affymetrix U133 GeneChip®arrays (Affymetrix, Inc., www.affymetrix.com). These arrays have probesets for the whole human genome immobilized on the chip, and can be usedto determine up- and down-regulation of genes in test samples. Othersubstrates having affixed thereon human genomic DNA or probes capable ofdetecting expression products, such as those available from Affymetrix,Agilent Technologies, Inc. (www.agilent.com) or Illumina, Inc.(www.illumina.com), also may be used. Currently preferred genemicroarrays for use in the present invention include Affymetrix U133GeneChip® arrays and Agilent Technologies genomic cDNA microarrays.Instruments and reagents for performing gene expression analysis arecommercially available. See, e.g., Affymetrix GeneChip® System(www.affymetrix.com). The expression data obtained from the analysisthen is input into the database.

In the second arm of the present method, chromosomal insertion/deletiondata for the genes of each sample as compared to samples of normaltissue was obtained. The insertion/deletion analysis was generated usingan array-based comparative genomic hybridization (“CGH”). Array CGHmeasures copy-number variations at multiple loci simultaneously,providing an important tool for studying cancer and developmentaldisorders and for developing diagnostic and therapeutic targets.Microchips for performing array CGH are commercially available, e.g.,from Agilent Technologies. The Agilent chip is a chromosomal array whichshows the location of genes on the chromosomes and provides additionaldata for the gene signature. The insertion/deletion data from thistesting is input into the database.

The analyses are carried out on the same samples from the same patientsto generate parallel data. The same chips and sample preparation areused to reduce variability.

The expression of certain genes known as “reference genes” “controlgenes” or “housekeeping genes” also is determined, preferably at thesame time, as a means of ensuring the veracity of the expressionprofile. Reference genes are genes that are consistently expressed inmany tissue types, including cancerous and normal tissues, and thus areuseful to normalize gene expression profiles. See, e.g., Silvia et al.,BMC Cancer, 6:200 (2006); Lee et al., Genome Research, 12(2):292-297(2002); Zhang et al., BMC Mol. Biol., 6:4 (2005). Determining theexpression of reference genes in parallel with the genes in the uniquegene expression profile provides further assurance that the techniquesused for determination of the gene expression profile are workingproperly. The expression data relating to the reference genes also isinput into the database. In a currently preferred embodiment, thefollowing genes are used as reference genes: ACTB, GAPD, GUSB, RPLP0and/or TRFC.

Data Correlation

The differential expression data and the insertion/deletion data in thedatabase are correlated with the clinical outcomes informationassociated with each tissue sample also in the database by means of analgorithm to determine a gene expression profile for determiningtherapeutic efficacy of irinotecan, as well as late recurrence ofdisease and/or disease-related death associated with irinotecan therapy.Various algorithms are available which are useful for correlating thedata and identifying the predictive gene signatures. For example,algorithms such as those identified in Xu et al., A Smooth ResponseSurface Algorithm For Constructing A Gene Regulatory Network, Physiol.Genomics 11:11-20 (2002), the entirety of which is incorporated hereinby reference, may be used for the practice of the embodiments disclosedherein.

Another method for identifying gene expression profiles is through theuse of optimization algorithms such as the mean variance algorithmwidely used in establishing stock portfolios. One such method isdescribed in detail in the patent application US Patent ApplicationPublication No. 2003/0194734. Essentially, the method calls for theestablishment of a set of inputs expression as measured by intensity)that will optimize the return (signal that is generated) one receivesfor using it while minimizing the variability of the return. Thealgorithm described in Irizarry et al., Nucleic Acids Res., 31:e15(2003) also may be used. The currently preferred algorithm is the JMPGenomics algorithm available from JMP Software (www.jmp.com).

The process of selecting gene expression profiles also may include theapplication of heuristic rules. Such rules are formulated based onbiology and an understanding of the technology used to produce clinicalresults, and are applied to output from the optimization method. Forexample, the mean variance method of gene signature identification canbe applied to microarray data for a number of genes differentiallyexpressed in subjects with colorectal cancer. Output from the methodwould be an optimized set of genes that could include some genes thatare expressed in peripheral blood as well as in diseased tissue. Ifsamples used in the testing method are obtained from peripheral bloodand certain genes differentially expressed in instances of cancer couldalso be differentially expressed in peripheral blood, then a heuristicrule can be applied in which a portfolio is selected from the efficientfrontier excluding those that are differentially expressed in peripheralblood. Of course, the rule can be applied prior to the formation of theefficient frontier by, for example, applying the rule during datapre-selection.

Other heuristic rules can be applied that are not necessarily related tothe biology in question. For example, one can apply a rule that only acertain percentage of the portfolio can be represented by a particulargene or group of genes. Commercially available software such as theWagner software readily accommodates these types of heuristics (WagnerAssociates Mean-Variance Optimization Application, www.wagner.com). Thiscan be useful, for example, when factors other than accuracy andprecision have an impact on the desirability of including one or moregenes.

As an example, the algorithm may be used for comparing gene expressionprofiles for various genes (or portfolios) to ascribe prognoses. Thegene expression profiles of each of the genes comprising the portfolioare fixed in a medium such as a computer readable medium. This can takea number of forms. For example, a table can be established into whichthe range of signals (e.g., intensity measurements) indicative ofdisease is input. Actual patient data can then be compared to the valuesin the table to determine whether the patient samples are normal ordiseased. In a more sophisticated embodiment, patterns of the expressionsignals (e.g., fluorescent intensity) are recorded digitally orgraphically. The gene expression patterns from the gene portfolios usedin conjunction with patient samples are then compared to the expressionpatterns. Pattern comparison software can then be used to determinewhether the patient samples have a pattern indicative of recurrence ofthe disease. Of course, these comparisons can also be used to determinewhether the patient is not likely to experience disease recurrence. Theexpression profiles of the samples are then compared to the portfolio ofa control cell. If the sample expression patterns are consistent withthe expression pattern for recurrence of a colorectal cancer then (inthe absence of countervailing medical considerations) the patient istreated as one would treat a relapse patient. If the sample expressionpatterns are consistent with the expression pattern from thenormal/control cell then the patient is diagnosed negative forcolorectal cancer.

A method for analyzing the gene signatures of a patient to determineprognosis of cancer is through the use of a Cox hazard analysis program.The analysis may be conducted using S-Plus software (commerciallyavailable from Insightful Corporation, www.insightful.com). Using suchmethods, a gene expression profile is compared to that of a profile thatconfidently represents relapse (i.e., expression levels for thecombination of genes in the profile is indicative of relapse). The Coxhazard model with the established threshold is used to compare thesimilarity of the two profiles (known relapse versus patient) and thendetermines whether the patient profile exceeds the threshold. If itdoes, then the patient is classified as one who will relapse and isaccorded treatment such as adjuvant therapy. If the patient profile doesnot exceed the threshold then they are classified as a non-relapsingpatient. Other analytical tools can also be used to answer the samequestion such as, linear discriminate analysis, logistic regression andneural network approaches. See, e.g., software available from JMPstatistical software (wwwjmp.com).

Numerous other well-known methods of pattern recognition are available.The following references provide some examples:

Weighted Voting: Golub, T R., Slonim, D K., Tamaya, P., Huard, C.,Gaasenbeek, M., Mesirov, J P., Coller, H., Loh, L., Downing, J R.,Caligiuri, M A., Bloomfield, C D., Lander, E S. Molecular classificationof cancer: class discovery and class prediction by gene expressionmonitoring. Science 286:531-537, 1999.

Support Vector Machines: Su, A I., Welsh, J B., Sapinoso, L M., Kern, SG., Dimitrov, P., Lapp, H., Schultz, P G., Powell, S M., Moskaluk, C A.,Frierson, H F. Jr., Hampton, G M. Molecular classification of humancarcinomas by use of gene expression signatures. Cancer Research61:7388-93, 2001. Ramaswamy, S., Tamayo, P., Rifkin, R., Mukherjee, S.,Yeang, C H., Angelo, M., Ladd, C., Reich, M., Latulippe, E., Mesirov, JP., Poggio, T., Gerald, W., Loda, M., Lander, E S., Gould, T R.Multiclass cancer diagnosis using tumor gene expression signaturesProceedings of the National Academy of Sciences of the USA98:15149-15154, 2001.

K-nearest Neighbors: Ramaswamy, S., Tamayo, P., Rifkin, R., Mukherjee,S., Yeang, C H., Angelo, M., Ladd, C., Reich, M., Latulippe, E.,Mesirov, J P., Poggio, T., Gerald, W., Loda, M., Lander, E S., Gould, TR. Multiclass cancer diagnosis using tumor gene expression signaturesProceedings of the National Academy of Sciences of the USA98:15149-15154, 2001.

Correlation Coefficients: van't Veer L J, Dai H, van de Vijver M J, He YD, Hart A A, Mao M, Peterse H L, van der Kooy K, Marton M J, Witteveen AT, Schreiber G J, Kerkhoven R M, Roberts C, Linsley P S, Bernards R,Friend S H. Gene expression profiling predicts clinical outcome ofbreast cancer, Nature. 2002 Jan. 31; 415(6871):530-6.

The gene expression analysis identifies a gene expression profile (GEP)unique to the cancer samples, that is, those genes which aredifferentially expressed by the cancer cells. This GEP then isvalidated, for example, using real-time quantitative polymerase chainreaction (RT-qPCR), which may be carried out using commerciallyavailable instruments and reagents, such as those available from AppliedBiosystems (www.appliedbiosystems.com).

In the present instance, the results of the gene expression analysisshowed that in colon cancer patients who were responsive to treatmentwith irinotecan, the following genes were up-regulated: ERBB2, GRB7,JNK1 kinase, BCL2, MK167, phospho-Akt, CD-68 and BAG1, and the followinggenes were down-regulated: Erk1 kinase, pospho-GSK-3beta, MMP11, CTSL2,CCNB1, BIRC5, STK6, MRP14 and GSTM1, compared with expression of thesegenes in the normal colon tissue samples from these patients, and fromthe negative control patients, i.e., the tissue samples from patientsthat had experienced a recurrence of their cancer after treatment withirinotecan. Reference genes ACTB, GAPD, GUSB, RPLP0 and TFRC all wereup-regulated.

Determination of Protein Expression Profiles

Not all genes expressed by a cell are translated into proteins,therefore, once a GEP has been identified, it is desirable to ascertainwhether proteins corresponding to some or all of the differentiallyexpressed genes in the GEP also are differentially expressed by the samecells or tissue. Therefore, protein expression profiles (PEPs) aregenerated from the same cancer and control tissues used to identify theGEPs. PEPs also are used to validate the GEP in other colon cancerpatients.

The preferred method for generating PEPs according to the presentinvention is by immunohistochemistry (IHC) analysis. In this methodantibodies specific for the proteins in the PEP are used to interrogatetissue samples from colon cancer patients. Other methods for identifyingPEPs are known, e.g. in situ hybridization (ISH) using protein-specificnucleic acid probes. See, e.g., Hofer et al., Clin. Can. Res.,11(16):5722 (2005); Volm et al., Clin. Exp. Metas., 19(5):385 (2002).Any of these alternative methods also could be used.

In the present instance, samples of colon tumor tissue and normal colontissue were obtained from patients afflicted with colon cancer who hadundergone successful treatment with irinotecan; these are the samesamples used for identifying the GEP. The tissue samples were arrayed ontissue microarrays (TMAs) to enable simultaneous analysis. TMAs consistof substrates, such as glass slides, on which up to about 1000 separatetissue samples are assembled in array fashion to allow simultaneoushistological analysis. The tissue samples may comprise tissue obtainedfrom preserved biopsy samples, e.g., paraffin-embedded or frozentissues. Techniques for making tissue microarrays are well-known in theart. See, e.g., Simon et al., BioTechniques, 36(1):98-105 (2004);Kallioniemi et al, WO 99/44062; Kononen et al., Nat. Med., 4:844-847(1998). In the present instance, a hollow needle was used to removetissue cores as small as 0.6 mm in diameter from regions of interest inparaffin embedded tissues. The “regions of interest” are those that havebeen identified by a pathologist as containing the desired diseased ornormal tissue. These tissue cores then were inserted in a recipientparaffin block in a precisely spaced array pattern. Sections from thisblock were cut using a microtome, mounted on a microscope slide and thenanalyzed by standard histological analysis. Each microarray block can becut into approximately 100 to approximately 500 sections, which can besubjected to independent tests.

The TMAs were prepared using two tissue samples from each patient: oneof colon tumor tissue and one of normal colon tissue. Control arraysalso were prepared; in a currently preferred embodiment, the followingcontrol TMAs were used: an array containing normal colon tissue samplesfrom healthy, cancer-free individuals; an array of “positive controls”containing tumor tissues from cancer patients afflicted with cancersother than colon cancer, e.g., breast cancer, lung cancer, prostatecancer, etc; and an array of “negative controls” containing tumorsamples from colon cancer patients that had experienced recurrences ofthe cancer after treatment with irinotecan—that is, patients who were“non-responders” to the therapy.

Proteins in the tissue samples may be analyzed by interrogating the TMAsusing protein-specific agents, such as antibodies or nucleic acidprobes, such as aptamers. Antibodies are preferred for this purpose dueto their specificity and availability. The antibodies may be monoclonalor polyclonal antibodies, antibody fragments, and/or various types ofsynthetic antibodies, including chimeric antibodies, or fragmentsthereof. Antibodies are commercially available from a number of sources(e.g., Abcam (www.abcam.com), Cell Signaling Technology(www.cellsignal.com), Santa Cruz Biotechnology (www.santacruz.com)), ormay be generated using techniques well-known to those skilled in theart. The antibodies typically are equipped with detectable labels, suchas enzymes, chromogens or quantum dots, that permit the antibodies to bedetected. The antibodies may be conjugated or tagged directly with adetectable label, or indirectly with one member of a binding pair, ofwhich the other member contains a detectable label. Detection systemsfor use with are described, for example, in the website of VentanaMedical Systems, Inc. (www.ventanamed.com). Quantum dots areparticularly useful as detectable labels. The use of quantum dots isdescribed, for example, in the following references: Jaiswal et al.,Nat. Biotechnol., 21:47-51 (2003); Chan et al., Curr. Opin. Biotechnol.,13:40-46 (2002); Chan et al., Science, 281:435-446 (1998).

The use of antibodies to identify proteins of interest in the cells of atissue, referred to as immunohistochemistry (IHC), is well established.See, e.g., Simon et al., BioTechniques, 36(1):98 (2004); Haedicke etal., BioTechniques, 35(1):164 (2003), which are hereby incorporated byreference. The IHC assay can be automated using commercially availableinstruments, such as the Benchmark instruments available from VentanaMedical Systems, Inc. (www.ventanamed.com).

In the present instance, the TMAs were contacted with antibodiesspecific for the proteins encoded by the genes identified in the geneexpression study as being up- or down-regulated in colon cancer patientswho were responders to therapy with irinotecan in order to determineexpression of these proteins in each type of tissue. The results of theIHC assay showed that in colon cancer patients who were responsive totreatment with irinotecan, the following proteins were up-regulated:ERBB2, GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD-68 and BAG1, andthe following proteins were down-regulated: Erk1 kinase,pospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1,compared with expression of these proteins in the normal colon tissuesamples from these patients, and in the negative control samples, i.e.,colon tumor samples from patients that had experienced a recurrence oftheir cancer after treatment with irinotecan (non-responders).Additionally, IHC analysis showed that a majority of these proteins werenot up- or down-regulated in the positive control tissue samples. Thereference proteins ACTB, GAPD, GUSB, RPLP0 and TFRC all wereup-regulated.

Assays

The present invention further comprises methods and assays fordetermining whether a colon cancer patient is likely to respond totreatment with irinotecan, and/or to predict whether the cancer islikely to recur, or disease-related death. According to one aspect, aformatted IHC assay can be used for determining if a colon cancer tumorexhibits the present GPEP. The assays may be formulated into kits thatinclude all or some of the materials needed to conduct the analysis,including reagents (antibodies, detectable labels, etc.) andinstructions.

The assay method of the invention comprises contacting a tumor samplefrom a colon cancer patient with a group of antibodies specific for someor all of the genes or proteins in the present GPEP, and determining theoccurrence of up- or down-regulation of these genes or proteins in thesample. The use of TMAs allows numerous samples, including controlsamples, to be assayed simultaneously.

In a preferred embodiment, the method comprises contacting a tumorsample from a colon cancer patient and control samples with a group ofantibodies specific for some or all of the proteins in the present GPEP,and determining the occurrence of up- or down-regulation of theseproteins. Up-regulation of some or all of the following proteins: ERBB2,GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD68 and BAG1; anddown-regulation of some or all of the following proteins: Erk1 kinase,phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1, isindicative of the patient's responsiveness to irinotecan. Preferably, atleast about four, preferably between about four and ten, and mostpreferably between about ten and sixteen (or more) antibodies are usedin the present method.

The method preferably also includes detecting and/or quantitatingcontrol or “reference proteins”. Detecting and/or quantitating thereference proteins in the samples normalizes the results and thusprovides further assurance that the assay is working properly. In acurrently preferred embodiment, antibodies specific for one or more ofthe following reference proteins are included: ACTB, GAPD, GUSB, RPLP0and/or TRFC.

The present invention further comprises a kit containing reagents forconducting an IHC analysis of tissue samples or cells from colon cancerpatients, including antibodies specific for at least four of theproteins in the GPEP and for any reference proteins. The antibodies arepreferably tagged with means for detecting the binding of the antibodiesto the proteins of interest, e.g., detectable labels. Preferreddetectable labels include fluorescent compounds or quantum dots, howeverother types of detectable labels may be used. Detectable labels forantibodies are commercially available, e.g. from Ventana MedicalSystems, Inc. (www.ventanamed.com).

Immunohistochemical methods for detecting and quantitating proteinexpression in tissue samples are well known. Any method that permits thedetermination of expression of several different proteins can be used.See. e.g., Signoretti et al., “Her-2-neu Expression and ProgressionToward Androgen Independence in Human Prostate Cancer,” J. Natl. CancerInstit., 92(23):1918-25 (2000); Gu et al., “Prostate stem cell antigen(PSCA) expression increases with high gleason score, advanced stage andbone metastasis in prostate cancer,” Oncogene, 19:1288-96 (2000). Suchmethods can be efficiently carried out using automated instrumentsdesigned for immunohistochemical (IHC) analysis. Instruments for rapidlyperforming such assays are commercially available, e.g., from VentanaMolecular Discovery Systems (www.ventanadiscovery.com) or Lab VisionCorporation (www.labvision.com). Methods according to the presentinvention using such instruments are carried out according to themanufacturer's instructions.

Protein-specific antibodies for use in such methods or assays arereadily available or can be prepared using well-established techniques.Antibodies specific for the proteins in the GPEP disclosed herein can beobtained, for example, from Cell Signaling Technology, Inc.(www.cellsignal.com), Santa Cruz Biotechnology, Inc.(www.santacruzbiotechnology.com) or Abcam (www.abcam.com).

The present invention is illustrated further by the followingnon-limiting Examples.

EXAMPLES

A series of prognostic factors were tested in order to validate theefficacy of the gene/protein expression profile (GPEP) of the presentinvention for predicting the therapeutic response of irinotecan therapy.The expression levels of these factors, consisting of the twenty-two(22) proteins in the present GPEP listed in Table 2 (which includesseventeen differentially expressed proteins and five referenceproteins), was determined by an immunohistochemical methodology inbiopsy tissue samples obtained from late-stage colon cancer patientswhose treatment with irinotecan had been successful, as well as samplesfrom patients whose treatment was unsuccessful, e.g., who hadexperienced late recurrence (LRec) or disease-related death (DRD)associated with the therapy. For purposes of selecting the patients forthe study, irinotecan therapy was determined to have failed if arecurrence was present within three years of diagnosis.

According to the current prescribing information for CAMPTOSAR®,irinotecan currently is indicated for first line therapy of colon cancerin combination with 5-fluorouracil (5-FU) and leucovorin, or followinginitial 5-FU therapy in late stage colon cancer patients. The patientsin the study had been treated using the combination therapy according tothe prescribing information for CAMPTOSAR®.

Gene/Protein Expression Profile (GPEP):

In this study, formalin fixed paraffin embedded primary colon cancerspecimens from 280 patients (median age 63 years) followed for a minimumof 120 months were evaluated for primary tumor size, histologic gradeand Duke's status. These patients included only those who had beenresponsive to irinotecan therapy. No patients received adjuvanttreatment prior to the first episode of disease recurrence. Using thetechniques described above, a GPEP was generated, consisting of thefollowing seventeen genes and encoded proteins: ERBB2, GRB7, JNK1kinase, BCL2, MK167, phospho-Akt, CD68, BAG1, Erk1 kinase,phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1,and five reference genes and proteins: ACTB, GAPD, GUSB, RPLP0 and TRFC.

Tissue microarrays were prepared using the colon adenocarcinomas andnormal (non-cancerous) colon tissue from patients described above havinglate stage cancers who were treated with irinotecan. TMAs also wereprepared containing positive and negative control samples. The TMAs usedin this study are described in Table A: TABLE A Tissue Micro ArraysNormal This array contained samples of normal (non- Screening cancerous)colon tissue from 200 patients (2 Array samples per patient). Colon Thisarray contained 280 patient samples Treatment obtained from the patientsafflicted with late- Irinotecan stage colon adenocarcinoma who had beentreated with CAMPTOSAR ® together with normal colon tissue samples fromeach patient. Cancer This array contained 200 tumor samples forScreening cancers other than colon cancer, including Survey Array breastcancer, pancreatic cancer, prostate (Positive cancer, ovarian cancer,salivary gland cancer, control array) lung cancer and brain tumor. ColonCancer This array contained samples of colon cancer Progression tissuefrom thirty patients who had progressed (Negative control to the nextstage of cancer or experienced a array - recurrence of cancer aftertreatment with TE30 array) CAMPTOSAR ®.

The TMAs were constructed according to the following procedure:

Construction: An instrument was used for creating holes in a recipientparaffin block that are then filled with tissue core acquired from aselected donor block. These tissue cores were punched with a thinwalled, sharpened borer. An X-Y precision guide allowed for the orderlyplacement of these tissue samples in an array format.

Presentation: TMA sections were cut at 4 microns and mounted onpositively charged glass microslides. Individual elements are 0.6 mm indiameter, spaced 0.2 mm apart.

Elements: In addition to TMAs containing the colon cancer samples,screening and control arrays were prepared containing the tissue samplesdescribed in Table A.

Specificity: The TMAs were designed for use with specialty staining andimmunohistochemical methods for gene expression screening purposes byusing monoclonal and polyclonal antibodies over a wide range ofcharacterized tissue types.

Accompanying each array was an array locator map and spreadsheetcontaining patient diagnostic, histologic and demographic data for eachelement.

Immunohistochemical (IHC) staining techniques were used for thevisualization of tissue (cell) proteins present in the tissue samples onthe TMAs. These techniques were based on the immunoreactivity ofantibodies and the chemical properties of enzyme or enzyme complexes,which react with colorless substrate-chromogens to produce a colored endproduct. Initial immunoenzymatic stains utilized the direct method,which conjugated directly to an antibody with known antigenicspecificity (primary antibody).

A modified labeled avidin-biotin technique was employed in which abiotinylated secondary antibody formed a complex withperoxidase-conjugated strepavidin molecules. Endogenous peroxidaseactivity was quenched by the addition of 3% hydrogen peroxide. Thespecimens then were incubate with the primary antibodies followed bysequential incubations with the biotinylated secondary link antibody(containing anti-rabbit or anti-mouse immunoglobulins) and peroidaselabeled strepavidin. The primary antibody, secondary antibody, andavidin enzyme complex is then visualized utilizing a substrate-chromogenthat produces a brown pigment at the antigen site that is visible bylight microscopy. The antibodies utilized in this study were antibodiesspecific for the proteins in the present protein expression profile,i.e., ERBB2, GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD68, BAG1,Erk1 kinase, phospho-GSK-3beta, MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14and GSTM1, and reference proteins ACTB, GAPD, GUSB, RPLP0 and TRFC. Allantibodies were obtained from Cell Signaling Technology, Inc., andAbcam.

Automated IHC Staining Procedure:

-   -   1. Heat-induced epitope retrieval (HIER) using 10 mM Citrate        buffer solution. pH 6.0, was performed as follows:        -   a. Deparaffinized and rehydrated sections were placed in a            slide staining rack.        -   b. The rack was placed in a microwaveable pressure cooker,            750 ml of 10 mM Citrate buffer pH 6.0 was added to cover the            slides.        -   c. The covered pressure cooker was placed in the microwave            on high power for 15 minutes.        -   d. The pressure cooker was removed from the microwave and            cooled until the pressure indicator drops and the cover            could be safely removed.        -   e. The slides were allowed to cool to room temperature (RT),            and IHC staining was carried out.    -   2. Slides were treated with 3% H₂O₂ for 10 min. at RT to quench        endogenous peroxidase activity.    -   3. Slides were gently rinsed with phosphate buffered saline        (PBS).    -   4. The primary antibodies were applied at the predetermined        dilution (according to Cell Signaling Technology's        specifications) for 30 min. at RT. Normal mouse or rabbit serum        1:750 dilution was applied to negative control slides.    -   5. Slides were gently rinsed with phosphate buffer saline (PBS).    -   6. Secondary biotinylated link antibodies (secondary antibodies:        biotinylated anti-chicken and anti-mouse immunoglobulins in        phosphate buffered saline (PBS), containing carrier protein and        1.5 mM sodium azide) were applied for 30 min. at RT.    -   7. Slides were rinsed with phosphate buffered saline (PBS).    -   8. The slides were treated with streptavidin-HRP (streptavidin        conjugated to horseradish peroxidase in PBS containing carrier        protein and anti-microbial agents from Ventana.) for 30 min. at        room temperature.    -   9. Slides were rinsed with phosphate buffered saline (PBS).    -   10. The slides were treated with substrate/chromogen        (substrate-imidazole-HCl buffer pH 7.5 containing H₂O₂ and        anti-microbial agents; DAB-3,3′-diaminobenzidine in chromogen        solution from Ventana) for 10 min. at room temperature.    -   11. Slides were rinsed with distilled water.    -   12. Counterstain in Hematoxylin was applied for 1 min.    -   13. Slides were washed in running water for 2 min.    -   14. The slides were then dehydrated, cleared and the coverglass        was mount.

All primary antibodies were titrated to dilutions according to themanufacturer's specifications. Staining of the TE30 test array slides(described below) was performed both with and without epitope retrieval(HIER). The slides were screened by a pathologist to determine theoptimal working dilution. Pretreatment with HIER, provided strongspecific staining with little to no background. The above-described IHCprocedure was carried out using a Benchmark instrument from VentanaMedical Systems, Inc.

Scoring Criteria:

Staining was scored by a pathologist on a 0-3+ scale, with 0=nostaining, and trace being less than 1+ but greater than 0. The scoringprocedures are described in Signoretti, et al., J. Nat. Cancer Inst.,vol. 92(23):1918 (December 2000) and Gu, et al., Oncogene, vol. 19, p.1288 (2000). Grades of 1+ to 3+ represent increased intensity ofstaining with 3+ being strong, dark brown staining. Scoring criteria wasalso based on total percentage of staining 0=0%, 1=less than 25%,2=25-50% and 3=greater than 50%. The percent positivity and theintensity of staining for both Nuclear and Cytoplasmic as well assub-cellular components were analyzed. Both the intensity and percentagepositive scores were multiplied to produce one number 0-9. 3+ stainingwas determined from known expression of the antigen from the positivecontrols.

Positive tissue controls were defined via standard Western Blotanalysis. This experiment was performed to confirm the level of proteinexpression in each of the control tissues. Negative controls also weredefined by the same methodology. The positive controls consisted ofbreast, prostate, bung, salivary gland, pancreas and ovarianadenocarcinomas and brain tumor tissue samples unrelated to the coloncancer patients who were the subjects of the study. Colon cancer tissuesamples from patients who were non-responsive to irinotecan therapy(i.e., who experienced recurrence of the disease or death from thedisease after treatment) were used as negative controls.

Positive expression also was evaluated using a xenograft array. SCIDmice were injected with tumor cells derived from patients who wereresponsive to treatment with irinotecan, and the tumors were allowed togrow in the mice. Once the tumors were established, the mice wereinjected with 200 mg/kg of irinotecan, and the mice were monitored toobserve responsiveness to the drug. As a result of treatment withirinotecan, the tumors formed in the SCID mice were reduced oreliminated. Prior to treatment with the drug, samples of the tumors wereextracted from the mice and used to make a TMA. IHC assay of the TMAcontaining the mouse xenograft tumor tissue showed that the xenografttumors have the same GPEP as that identified in the human patients whowere responsive to irinotecan therapy.

All runs were grouped by antibody and tissue arrays which ensured thatthe runs were normalized, meaning that all of the tissue arrays werestained under the same conditions with the same antibody on the samerun. The reproducibility was compared and validated.

Results:

Univariate analysis of GPEP profiles of the patient samples describedabove independently and accurately predicted response to irinotecantherapy (p<0.0001); late recurrence (LRec, p<0.0005); anddisease-related death (DRD, p<0.0001). When stratified into GPEPnegative, borderline positive and highly positive groups, patients withhighly positive tumors had a relative risk (adjusted relative hazard) ofirinotecan therapy response of 8.3 (range 2.1-32.4); LRec of 4.3 (range1.7-11.0) and DRD of 11.0 (range 3.0-40.7). Tumor size and histologicgrade did not predict irinotecan therapy response, LRec or DRD.

The results from this study demonstrate that in late stage colon cancerpatients, GPEP positivity by immunohistochemistry accurately predictedirinotecan therapy response, late disease recurrence and disease relateddeath independent of tumor size, grade and Duke's status. The testaccurately detected ninety-two percent (92%) of non-responders toirinotecan therapy (less than 1.5% error rate or mis-classification).For determining irinotecan responsiveness, the test sensitivity rate wasdetermined to be about ninety-six percent (96%), and the testspecificity rate to be about ninety-eight percent (98%). “GPEPpositivity” means that in the tumor samples from patients who wereresponders to irinotecan therapy, the following proteins wereup-regulated: ERBB2, GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD-68and BAG1, and the following genes and encoded proteins weredown-regulated: Erk1 kinase, phospho-GSK-3beta, MMP11, CTSL2, CCNB1,BIRC5, STK6, MRP14 and GSTM1, compared with expression of these genesand proteins in normal colon tissue from these patients and the normalcolon tissue and non-colon cancer tissues from other patients. Referenceproteins ACTB, GAPD, GUSB, RPLP0 and TFRC were up-regulated in alltissues.

The results from this study are illustrated in FIG. 1. FIG. 1 is a graphshowing the survival rates of colorectal cancer patients treated withirinotecan plotted against the presence of a GPEP of the invention. Asshown in FIG. 1, patients with tumors having a gene expression profilein which at least sixteen of the genes in the present GPEP weredifferentially expressed and had the longest survival rates aftertreatment with irinotecan. Patients whose gene expression profile showedthat ten or more of the genes in the GPEP had the next longest survivalrates. The survival rates of patients whose gene expression profilesindicated that four or fewer of these genes were differentiallyexpressed had the lowest survival rates after irinotecan therapy.

The twenty genes noted in the legend to FIG. 1 include five referenceproteins.

Validation Studies

Studies using additional colon cancer biopsy tissues (from patientsother than those used in the study described above) were performed tofurther validate the utility of the GPEP of the present invention inpredicting a patient's responsiveness to irinotecan therapy. In one suchstudy, formalin fixed paraffin embedded primary colon cancer specimensfrom 220 patients followed for a minimum of 120 months were evaluatedfor primary tumor size, histologic grade, Duke's status and expressionof the proteins in the present GPEP. None of these patients receivedadjuvant treatment prior to the first episode of disease recurrence. Thestudy was carried out using the same IHC methodology as described in thepreceding Example, and using the same negative and positive controlarrays.

Univariate analysis of GPEP profiles of the patient samples describedabove accurately predicted response to irinotecan therapy (p<0.0001);late recurrence (LRec, p<0.0005); and disease-related death (DRD,p<0.0001). When stratified into GPEP negative, borderline positive andhighly positive groups, patients with highly positive tumors had arelative risk (adjusted relative hazard) of irinotecan therapy responseof 6.7 (range 2.1-22.4); LRec of 3.3 (range 1.7-9.0) and DRD of 7.0(range 3.0-30.0).

The results from this study further validates that in late stage coloncancer patients, GPEP positivity accurately predicted irinotecan therapyresponse, late disease recurrence and disease related death independentof tumor size, grade and Duke's status. For determining irinotecanresponsiveness, the test sensitivity rate was determined to be aboutninety-six percent (96%), and the test specificity rate to be aboutninety-eight percent (98%).

1. A gene expression profile for determining if a patient is a responderto treatment with irinotecan comprising at least about four or moregenes selected from the group consisting of: ERBB2, GRB7, Erk1 kinase,JNK1 kinase, BCL2, MK167, phospho-Akt, CD68, BAG1, phospho-GSK-3beta,MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1.
 2. The geneexpression profile of claim 1 further comprising at least one referencegene.
 3. The gene expression profile of claim 2 wherein the referencegene is selected from the group consisting of: ACTB, GAPD, GUSB, RPLP0and TFRC.
 4. A method of determining if a patient is a responder totreatment with irinotecan comprising: a. obtaining colon cancer tissuefrom at least one patient diagnosed with colon cancer; and b.determining the presence or absence in the sample of a gene expressionprofile wherein at least about four or more genes selected from thegroup consisting of: ERBB2, GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt,CD68 and BAG1, are up-regulated and Erk1 kinase, phospho-GSK-3beta,MMP11, CTSL2, CCNB1, BIRC5, STK6, MRP14 and GSTM1 are down-regulated. 5.The method of claim 1 further comprising at least one reference gene. 6.The method of claim 5 wherein the reference gene is selected from thegroup consisting of: ACTB, GAPD, GUSB, RPLP0 and TFRC.
 7. A method ofdetermining if a patient is a responder to treatment with irinotecancomprising: a. obtaining colon cancer tissue from at least one patientdiagnosed with colon cancer; and b. determining the presence or absencein the sample of a protein expression profile wherein at least aboutfour or more proteins selected from the group consisting of: ERBB2,GRB7, JNK1 kinase, BCL2, MK167, phospho-Akt, CD68 and BAG1, areup-regulated and Erk1 kinase, phospho-GSK-3beta, MMP11, CTSL2, CCNB1,BIRC5, STK6, MRP14 and GSTM1 are down-regulated.
 8. The method of claim1 further comprising at least one reference protein.
 9. The method ofclaim 5 wherein the reference protein is selected from the groupconsisting of: ACTB, GAPD, GUSB, RPLP0 and TFRC.
 10. The method of claim7 wherein step (b) is performed using immunohistochemistry.